Recording Performance and Magnetization Time Decay for Super-fine Ba Ferrite Particle Media

Abstract

The high-density recording performance and thermal stability of super-fine particulate Ba-ferrite media are investigated. The smallest particles have an average diameter of 22.7 nm. In the first part of the paper, an excellent recording capability for small-particle media is described. A D₂₀* value greater than 250 kFRPI has been ascertained at the present spacing of 47 nm. Next, inter-particle interaction, determined through ΔM measurement, and thermal stability in terms of magnetization time decay measurement are discussed. The Street and Woolley method and the waiting time method are compared in relation to estimating the activation volume for super-fine particulate media. It is shown that inter-particle interaction greatly affects the magnetization time decay and activation volume.